Striga and Orobanche are root parasitic plants, which grow on agricultural crops such as leguminous crops and cereals as a host. Striga is distributed in semiarid regions of tropical and subtropical zones of Africa and South Asia, and grow on main agricultural crops such as sorghum and corn as a host. Orobanche is widely distributed in Mediterranean and Middle East regions centered on temperate and subarctic zones, and grow on leguminous crops and the like as a host. Root parasitic plants are parasitic in the roots of agricultural crops, and rob nutrients and water from the agricultural crops. As the result, the growth of the agricultural crops is inhibited. Accordingly, root parasitic plants cause great damage to agriculture, and such damage has recently spread to Europe and Australia.
In order to avoid being parasitic in the roots of agricultural crops, it is needed to kill seeds of root parasitic plants in field soil before the cultivation of agricultural crops in the field.
It is known that seeds of root parasitic plants are germinated in the vicinity of a host, and they are not survived in several days after the germination of seeds when they could not be parasitic in the roots of a host. Therefore, if the germination of seeds of root parasitic plants can be induced in agricultural lands before seeding of agricultural crops, i.e., in the absence of agricultural crops, the germinated seeds of root parasitic plants can be killed, and thus the growth inhibition of agricultural crops by root parasitic plants can be controlled.
Heretofore, some compounds capable of inducing the germination of seeds of root parasitic plants have been reported (cf. Non-Patent Literatures 1 and 2).